I have a thing for doppelgangers. Partly it's because my brain always falls for this trick, and believes on some level that the doubles are actually being played by different actors. And thanks to digital effects, doppelgangers are easier to do on TV shows like Orphan Black and Fringe, or low budget indie films like Moon and The One I Love. But doppelgangers are also multiplying because they tap into a very modern concern: social media. With Ryan Britt, Alissa Wilkinson and Elayne Tobin.